PIC16F84A 18-pin Enhanced Flash/EEPROM 8-Bit MCU Data Sheet

PIC16F84APPackaging .......................................................................... 55PICDEM-1 Low-Cost PICmicro Demo Board ..................... 36PICDEM-2 Low-Cost PIC16CXX Demo Board .................. 36PICDEM-3 Low-Cost PIC16CXXX Demo Board ................ 36PICSTART® Plus Entry Level Development System ........ 35Pinout Descriptions .............................................................. 4Pointer, FSR ....................................................................... 11PORTA ........................................................................... 4, 13Initializing ................................................................... 13PORTA Register ........................................ 7, 13, 14, 24RA3:RA0 Block Diagram ............................................ 13RA4 Block Diagram .................................................... 14RA4/T0CKI Pin ................................................. 4, 13, 17TRISA Register .................................... 7, 13, 14, 18, 24PORTB ........................................................................... 4, 15Initializing ................................................................... 15PORTB Register ........................................ 7, 15, 16, 24Pull-up Enable (RBPU Bit) ........................................... 9RB0/INT Edge Select (INTEDG Bit) ............................. 9RB0/INT Pin, External ...................................... 4, 16, 29RB3:RB0 Block Diagram ............................................ 15RB7:RB4 Block Diagram ............................................ 15RB7:RB4 Interrupt on Change ......................... 4, 15, 29RB7:RB4 Interrupt on Change Enable (RBIE Bit) ...... 10RB7:RB4 Interrupt on Change Flag (RBIF Bit) .... 10, 15TRISB Register .......................................... 7, 15, 16, 24Power-on Reset (POR) .......................................... 21, 23, 25Oscillator Start-up Timer (OST) ........................... 21, 25PD Bit ............................................. 8, 23, 28, 31, 32, 34Power-up Timer (PWRT) ..................................... 21, 25PWRT Enable (PWRTE Bit) ....................................... 21Time-out Sequence .................................................... 28Time-out Sequence on Power-up ........................ 26, 27TO Bit ....................................... 8, 23, 28, 30, 31, 32, 34Prescaler ............................................................................ 17Assignment (PSA Bit) ............................................ 9, 17Block Diagram ............................................................ 18Rate Select (PS2:PS0 Bits) ................................... 9, 17Switching Prescaler Assignment ................................ 18PRO MATE® II Universal Programmer .............................. 35Product Identification System ............................................. 67Program Counter ................................................................ 11PCL Register .................................................... 7, 11, 24PCLATH Register ............................................ 7, 11, 24Reset Conditions ........................................................ 24Program Memory ................................................................. 5General Purpose Registers .......................................... 6Interrupt Vector ...................................................... 5, 29Reset Vector ................................................................ 5Special Function Registers ...................................... 6, 7Programming, Device Instructions ..................................... 33RRAM. See Data MemoryReader Response .............................................................. 66Register File ......................................................................... 6Reset ............................................................................ 21, 23Block Diagram ............................................................ 23Reset Conditions for All Registers ............................. 24Reset Conditions for Program Counter ...................... 24Reset Conditions for STATUS Register ..................... 24WDT Reset. See Watchdog Timer (WDT)Revision History ................................................................. 59SSaving W Register and STATUS in RAM .......................... 29SEEVAL® Evaluation and Programming System .............. 37SLEEP ............................................................. 21, 23, 29, 31Software Simulator (MPLAB-SIM) ..................................... 37Special Features of the CPU ............................................. 21Special Function Registers .............................................. 6, 7Speed, Operating ..................................................... 1, 22, 49Stack .................................................................................. 11STATUS Register ................................................ 7, 8, 24, 29C Bit ....................................................................... 8, 34DC Bit .................................................................... 8, 34PD Bit ............................................ 8, 23, 28, 31, 32, 34Reset Conditions ....................................................... 24RP0 Bit .................................................................... 6, 8TO Bit ...................................... 8, 23, 28, 30, 31, 32, 34Z Bit ....................................................................... 8, 34TTime-out (TO) Bit. See Power-on Reset (POR)Timer0 ................................................................................ 17Block Diagram ........................................................... 17Clock Source Edge Select (T0SE Bit) ......................... 9Clock Source Select (T0CS Bit) .................................. 9Overflow Enable (T0IE Bit) .................................. 10, 29Overflow Flag (T0IF Bit) ................................ 10, 18, 29Overflow Interrupt ................................................ 18, 29RA4/T0CKI Pin, External Clock ................................. 17TMR0 Register ................................................ 7, 18, 24Timing DiagramsDiagrams and Specifications ..................................... 49Time-out Sequence on Power-up ........................ 26, 27WW Register ................................................................... 24, 29Wake-up from SLEEP ................................ 21, 25, 28, 29, 31Interrupts ............................................................. 31, 32MCLR Reset .............................................................. 31WDT Reset ................................................................ 31Watchdog Timer (WDT) ............................................... 21, 30Block Diagram ........................................................... 30Enable (WDTE Bit) .................................................... 21Programming Considerations .................................... 30RC Oscillator ............................................................. 30Time-out Period ......................................................... 30WDT Reset, Normal Operation .................................. 23WDT Reset, SLEEP ............................................ 23, 31WWW, On-Line Support ................................................ 2, 65DS35007A-page 64 Preliminary © 1998 Microchip Technology Inc.